Tuesday 15 March 2011

Ext.Net and Mono

I like ext.js/Sencha for having a rich client in the browser.

On the other hand, we are using Mono for running our .Net server.

ext.net is a good library that helps you to easily write web applications, based on your .net libraries.

For OpenPetra, I have created an online application system, and the backend for the registration office is written with ext.net.

Here are some problems I came across, and how I solved them:

First, I had to recompile the ext.net dlls and also the Newtonsoft.Json.Net20.dll.

The Newtonsoft.Json.Net20.dll has been compiled with the latest compiler built from Mono 2.8 trunk. This was necessary so that no Microsoft dlls were linked in.
The ext.net dll was built against the Mono compiled Newtonsoft.Json.Net20.dll on Windows with SharpDevelop. The mono compiler crashed on Linux when trying to build the ext.net solution.
The resulting files are available from the online source repository of OpenPetra, eg. http://bazaar.launchpad.net/~openpetracore/openpetraorg/trunkhosted/files/head:/csharp/ThirdParty/ext.net/

I was not able to get Ext.Net to run with the latest Mono 2.8, but it is working fine with 2.6.7.
I had to build it from the sources.
Some links related to the problems I had with Mono 2.8 and Ext.Net:
compile ext.net: There is no implicit reference conversion from `Ext.Net.ComboBox' to `Ext.Net.ComboBoxBase'

Running ext.net on Mono 2.8: get the error: Cannot add a Ext.Net.Parameter to System.String
For the moment, the solution for me was to use Mono 2.6.7.

The examples of ext.net only show the c# code inside the aspx file, but with growing size of the code it would be good to be able to split the code behind code from the UI code.
This is possible, but you need to define all controls in the .cs file, at least those you want to use in your code behind code.
In the aspx file, make sure you have at the top:
<%@ Page Language="C#"
src="Desktop.aspx.cs" %>
<%@ Register assembly="Ext.Net" namespace="Ext.Net" tagprefix="ext" %>
see the whole file here: OnlineRegistrationBackend/Desktop.aspx

Now I ran into errors like this when Mono was compiling the code on the fly:
Compiler Error Message: CS1644: Feature `anonymous types' cannot be used because it is not part of the C# 2.0 language specification
I found on the Internet this page: http://www.4guysfromrolla.com/articles/121207-1.aspx
linked from http://web.archiveorange.com/archive/v/c2PM7RMRJf7Ti7PP7uVb, where they discuss how to use "extension methods" and "collection initializers" with Mono.

I have added all those settings to my web.config, see the result here:

You can see a running demo here: http://demo.openpetra.org:8009/

Monday 7 March 2011

Knowledge Tree and PHP 5.3.3

We have got the latest PHP version on Hostsharing, and Knowledge Tree did not work anymore.
I got a long list of deprecated warnings, and the session would not even start, so not even a login screen is displayed.

Deprecated: Assigning the return value of new by reference is deprecated
Warning: The magic method __get() must have public visibility and cannot be static
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent

The solution is to edit config/dmsDefaults.php, find the lines containing
error_reporting(E_ALL & ~E_NOTICE);
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
Below that, add the following line:
Now Knowledge Tree will work again, and hopefully the next version of Knowledge Tree will have fixed all the deprecated PHP things.